以资源回收为目标的生物膜法富集除磷工艺的机制与调控研究

Municipal wastewater treatment plant will become an important carrier of recycling of resources, the recovery of organic matter and phosphorus will become the primary task of the next generation of sewage treatment plants. After the recovery of organic matter, the problem of low organic content will bring severe challenges to the enhanced biological phosphorus removal (EPBR) process. However, the current phosphorus recovery technology has the disadvantages of large amount of sludge, multiple cycles of phosphorus (anaerobic/aerobic/anaerobic) in activated sludge, and sludge return, which leads to higher energy consumption and carbon emissions. The biofilm for recovery phosphorus from wastewater has development potential because of its low need of organic and strong capacity of accumulating phosphorus. However, there is still a lack of systematic and in-depth study on the effective release mechanism of phosphorus and the organic requirement during the recovery process. We propose a new sequencing batch biofilm process with alternating aerobic/anaerobic operation to remove phosphate efficiently and obtain high concentration phosphate recovery solution. The objective of this study is to investigate the changes of microbial community and the morphology and composition of phosphate in the uptake and release process, the mechanism of concentrating and release of phosphate by biofilm process, the relationship between the carbon source (or other operating conditions) and the change of phosphorus forms in the biofilm, and the key influencing factors. The operation and control conditions of simultaneous removal and concentration of phosphate by the biofilm process will also be proposed. The result of this study can be used to simplify the current phosphorus removal and recovery process, and to provide theoretical and technical support for the construction of the wastewater treatment plant with recovery of resources and energy in future.

城市污水处理将成为资源循环利用的重要载体，有机物与磷的回收必成为下一代污水厂的首要任务。有机物回收带来的低碳源（有机物）问题，将对强化生物除磷主流工艺提出严峻挑战。而现行磷回收技术存在泥量大、磷多次在活性污泥的体内循环（厌氧-好氧-厌氧）、需污泥回流等特征导致了较高的能耗和碳排放。生物膜回收磷技术因为碳源要求低、较强蓄磷能力等特点具有发展潜力，但对生物膜内磷的有效释放机制以及回收过程中碳源需求仍缺乏系统和深入的研究。我们提出以序批式生物膜工艺同步高效去除磷酸盐并获取高浓度磷酸盐回收液。旨在研究生物膜中微生物种群变化规律，以及磷酸盐吸收与释放过程中的形态与组分变化，获取磷富集与释放机制；分析碳源等运行条件与生物膜中磷形态变化的响应关系，识别关键影响因素；提出生物膜同步去除并富集磷酸盐工艺的运行控制条件。用于简化现行除磷与回收工艺，并为构建未来资源与能源回收的城市污水厂提供理论与技术支撑。

污水处理厂面临着由去除磷向回收磷的使命转换，生物膜相较于传统EPBR工艺因其工艺简单、可实现主流工艺中同步去除并富集磷酸盐等特点具有发展潜力，但富集过程中碳源需求高、吸收-释放关键调控机制不清限制了该技术的发展与应用。本研究以序批式生物膜反应器（BSBR）为对象，考察了聚磷生物膜的驯化以及DO、HRT、温度等工艺条件对磷酸盐的富集性能影响；以31P NMR获取磷酸盐形态的转化规律，结合生物膜内多聚磷酸盐、PHA内聚物的变化揭示了生物膜的吸-释磷代谢与关键调控机制；并以宏基因组测序、代谢通路分析等分子生物手段解析了生物膜中优势聚磷菌变化规律及代谢特征。.研究表明，生物膜在低碳源消耗下最高可富集27.8倍于进水的磷酸盐溶液，磷总回收率可超过80%；研究发现提高生物膜的蓄磷水平有助于提高回收液磷浓度，随着DO提高，生物膜中PHA的分解量与速率、Poly-P的合成量均相应提高，揭示了高溶解氧水平是促进磷吸收/蓄积的重要调控因子；磷酸盐吸收与释放所需的还原力和ATP来源于EMP、ED、HMP和TCA循环，较EBPR工艺更具多样性；在单个厌氧周期中EPS的释磷量可达生物膜总释磷量的86.92%，而胞内释磷量仅占13.8%，证明了EPS在吸收和储存磷方面发挥着重要的作用。高通量测序表明系统中的优势聚磷菌主要为Flavobacterium和Dechloromonas、Candidatus Contendobacter。.本项目探明了生物膜除磷过程中影响好氧吸磷和厌氧释磷的关键调控因子，获取了好氧段DO浓度和厌氧段碳源浓度对反应器运行性能的影响及其代谢机制，进而明确了实现磷的同步去除-富集的最佳控制条件，并提出了通过提高微生物蓄磷量作为释磷动力的新途径，补充和完善了生物膜除磷领域的技术空白，并据此构建了面向城市污水厂磷回收的生物膜富集工艺及运行模式。